考虑围岩蠕变的锚固时空效应分析及控制技术

针对巷道锚杆锚索联合支护失效形式,基于围岩变形特征建立了能够反映围岩加速蠕变的本构模型以及锚杆工作特性的锚固体本构模型,通过求解出的锚固体蠕变方程分析锚固基础位置对围岩变形的控制作用,结果表明:锚杆支护对围岩的蠕变控制机理可概括为:分担围岩承受的载荷和等效增大围岩刚度,增强围岩抵抗变形能力两部分。充分发挥锚杆支护性能、延长锚杆支护时效、维持巷道处于稳定工作状态所需的空间需要同时满足两个条件:锚杆受载不超过杆体破断载荷,锚固基础位于塑性区之外;端锚形式的锚固基础位于弹性岩体中能够最大程度发挥支护系统的承载能力,端锚锚固形式的着力基础位于稳定的弹性围岩中,围岩变形后锚固基础能迅速发生锚固作用,优于全长锚固形式;可接长锚杆具有延伸率大、可灵活设置锚杆长度的优点,能解决蒲河矿西三采区集中运输大巷锚杆易发生滑脱失效、锚索易发生破断失效的问题。

Analysis of anchor space-time effect and research of control technology considering creep of surrounding rock

Aiming at the failure mode of combined support of roadways between rock bolt and cable bolt,the constitutive model of surrounding rock and the constitutive model of anchorage body,which can reflect the accelerated creep of surrounding rock and the working characteristics of rock bolt respectively,are established based on the deformation characteristics of surrounding rock.The control effect of anchorage foundation location on the deformation of surrounding rock is analyzed by solving the creep equation of anchorage body.The result shows that the creep control mechanism of bolt support to surrounding rock can be summarized in two aspects:the first is to share the load of surrounding rock,the second is to increase the stiffness of surrounding rock and enhance the resistance to the deformation of surrounding rock.Giving a full play to the supporting performance of rock bolt,lengthening the supporting time of rock bolt and maintaining the stable working state of roadway need to meet two criteria:the load of rock bolt does not exceed the critical breaking load of rod,meanwhile,the anchorage foundation should be located beyond the plastic zone.It can maximize the bearing capacity of support system when the anchorage foundation of end-anchored form is located in the elastic surrounding rock.Under this circumstance,the end-anchored form,whose stress foundation locates in elastic rock mass and whose anchoring effect can occur rapidly after the deformation of surrounding rock,is better than a full-length anchoring form.The butt long bolt has the advantages of large elongation and flexible anchor length,and it can solve the problems that the rock bolt of roadway,in the centralized transportation roadway of 3rd panel in western of Puhe coal-mine,is often pulled out and its cable bolt breaks easily.